Semiconductor light emitting device and method for manufacturing the same

ABSTRACT

Provided is a semiconductor light emitting device and a method for manufacturing the same. The semiconductor light emitting device comprises: a first conductive type semiconductor layer; an active layer on the first conductive type semiconductor layer; an undoped semiconductor layer on the active layer; a first delta-doped layer on the undoped semiconductor layer; and a second conductive type semiconductor layer on the first delta-doped layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 12/198,728filed on Aug. 26, 2008, now U.S. Pat. No. 7,700,961 and for whichpriority is claimed under 35 U.S.C. §120; and this application claimspriority of application Ser. No. 10-2007-0086711 filed in Korea on Aug.28, 2007 under 35 U.S.C. §119; the entire contents of all are herebyincorporated by reference.

BACKGROUND

The present disclosure relates to a semiconductor light emitting deviceand a method of manufacturing the same.

Groups III-V nitride semiconductors have been variously applied to anoptical device such as blue and green light emitting diodes (LED), ahigh speed switching device, such as a MOSFET (Metal Semiconductor FieldEffect Transistor) and an HEMT (Hetero junction Field EffectTransistors), and a light source of a lighting device or a displaydevice.

The nitride semiconductor is mainly used for the LED (Light EmittingDiode) or an LD (laser diode), and studies have been continuouslyconducted to improve the manufacturing process or a light efficiency ofthe nitride semiconductor.

SUMMARY

Embodiments provide a semiconductor light emitting device comprising anundoped semiconductor layer and a delta-doped layer on an active layer,and a method for manufacturing the same.

Embodiments provide a semiconductor light emitting device comprising anundoped semiconductor layer and at least two delta-doped layers on anactive layer, and a method for manufacturing the same.

Embodiments provide a semiconductor light emitting device and a methodfor manufacturing the same that can improve the conductivity andcrystallinity of a second conductive type semiconductor layer by forminga delta-doped layer using a second conductive type dopant.

An embodiment provides a semiconductor light emitting device comprising:a first conductive type semiconductor layer; an active layer on thefirst conductive type semiconductor layer; an undoped semiconductorlayer on the active layer; a first delta-doped layer on the undopedsemiconductor layer; and a second conductive type semiconductor layer onthe first delta-doped layer.

An embodiment provides a semiconductor light emitting device comprising:a first conductive type semiconductor layer; an active layer on thefirst conductive type semiconductor layer; an undoped semiconductorlayer on the active layer; and a second conductive type semiconductorlayer comprising a delta-doped layer on the undoped semiconductor layer.

An embodiment provides a method for manufacturing a semiconductor lightemitting device comprising: forming a first conductive typesemiconductor layer; forming an active layer on the first conductivetype semiconductor layer; forming an undoped semiconductor layer on theactive layer; forming a first delta-doped layer on the undopedsemiconductor layer; and forming a second conductive type semiconductorlayer on the first delta-doped layer.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a semiconductor light emitting deviceaccording to a first embodiment.

FIG. 2 is a side sectional view of a lateral type semiconductor lightemitting device using FIG. 1.

FIG. 3 is a side sectional view of a vertical type semiconductor lightemitting device using FIG. 1.

FIG. 4 is a side sectional view of a semiconductor light emitting deviceaccording to a second embodiment.

FIG. 5 is a side sectional view of a lateral type semiconductor lightemitting device using FIG. 4.

FIG. 6 is a side sectional view of a vertical type semiconductor lightemitting device using FIG. 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A semiconductor light emitting device and a method for manufacturing thesame according to an embodiment will be described in detail withreference to the accompanying drawings.

In the description of embodiments, it will be understood that when alayer (or film) is referred to as being ‘on’ another layer or substrate,it can be directly on another layer or substrate, or intervening layersmay also be present. Further, it will be understood that when a layer isreferred to as being ‘under’ another layer, it can be directly underanother layer, and one or more intervening layers may also be present.In addition, it will also be understood that when a layer is referred toas being ‘between’ two layers, it can be the only layer between the twolayers, or one or more intervening layers may also be present.

FIG. 1 is a side sectional view of a semiconductor light emitting deviceaccording to a first embodiment.

Referring to FIG. 1, the semiconductor light emitting device 100comprises a substrate 110, a buffer layer 120, a first conductive typesemiconductor layer 130, an active layer 140, an undoped semiconductorlayer 150, a delta-doped layer 155, and a second conductive typesemiconductor layer 160.

The substrate 110 may be made of one selected from the group consistingof sapphire (Al₂O₃), GaN, SiC, ZnO, Si, GaP, GaAs and InP, or maycomprise a conductive substrate. However, the material of the substrate110 is not limited to the aforementioned examples. The substrate 110 mayhave an irregular surface pattern.

A nitride semiconductor is grown on the substrate 110. The growth of thenitride semiconductor may be performed by an e-beam evaporator, a PVD(Physical vapor deposition) equipment, a CVD (Chemical vapor deposition)equipment, a PLD (Plasma laser deposition) equipment, a dual-typethermal evaporator, a sputter, an MOCVD (Metal organic chemical vapordeposition) equipment or the like, but the present invention is notlimited thereto.

The buffer layer 120 may be formed on the substrate 110. The bufferlayer 120 is a layer to decrease a difference in lattice constant fromthe substrate 110, and may be selectively formed of GaN, AlN, AlGaN,InGaN or the like.

An undoped GaN layer (not shown) may be formed on the buffer layer 120.The undoped GaN layer may be used as a substrate on which a nitridesemiconductor is grown. At least one of the buffer layer 120 and theundoped semiconductor layer may be formed or both of the buffer layer120 and the undoped semiconductor layer may not be formed. However, thepresent invention is not limited thereto.

The first conductive type semiconductor layer 130 is formed on thebuffer layer 120. The first conductive type semiconductor layer 130 mayfunction as a first electrode contact layer and is doped with a firstconductive type dopant. The first conductive type semiconductor layer130 may be an N-type semiconductor layer, which is a III-V compound andmay be formed of a semiconductor material having a composition formulaof In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0 x+y≦1). For example, theN-type semiconductor layer may be formed of at least one selected fromthe group consisting of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN.The first conductive type dopant is an N-type dopant, which comprisesSi, Ge and Sn.

Alternatively, a dopant-doped semiconductor layer may be further formedbetween the buffer layer 120 and the first conductive type semiconductorlayer 130, but the present invention is not limited thereto.

The active layer 140 comprising a single quantum well structure or amultiple quantum well structure is formed on the first conductive typesemiconductor layer 130. The active layer 140 may be formed in astructure in which InGaN well layers and AlGaN barrier layers arealternated or in a structure in which InGaN well layers and GaN barrierlayers are alternated, and these light emitting materials may be changedaccording to light emitting wavelengths, such as blue wavelength, redwavelength, green wavelength, etc.

A conductive cladding layer (not shown) may be formed on or/and underthe active layer 140, and may be an AlGaN layer.

The undoped semiconductor layer 150 may be formed on the active layer140, the delta-doped layer 155 may be formed on the undopedsemiconductor layer 150, and the second conductive type semiconductorlayer 160 may be formed on the delta-doped layer 155.

The undoped semiconductor layer 150 may be, for example, an undoped GaNlayer. The undoped semiconductor layer 150 protects the active layer 140from a second conductive type dopant.

The undoped GaN layer exemplified as the undoped semiconductor layer 150may be, for example, grown in a crystal growth chamber in a thickness of5˜200 {hacek over (A)} by supplying gas sources of NH₃ and TMGa (orTEGa) at a growing temperature of 700˜1000° C. Herein, the growthtemperature of the undoped semiconductor layer 150 may be set to atemperature range that can minimize a thermal damage to the active layer140.

An undoped Al_(y)GaN layer (0<y<0.5) may be grown on the undopedsemiconductor layer 150. The undoped Al_(y)GaN layer (0<y<0.5) is formedto prevent an operating voltage from being elevated, and is formed bysupplying gas sources of NH₃, TMGa (or TEGa) and TMAl.

The delta-doped layer 155 may be formed at a thickness of 1˜2 atomiclayers (ex: 0.2˜0.5 nm) by delta-doping a second conductive type dopant.The second conductive type dopant may comprise a P-type dopant, and theP-type dopant may comprise at least one selected from the groupconsisting of Mg, Zn, Ca, Sr and Ba.

The delta-doped layer 155 may be grown using Mg dopant. For example, anMg delta-doped layer is grown by stopping the supply of a gas source oftrimethylgalium (TMGa) (or TEGa), exhausting the TMGa (or TEGa) gas toan outside, and supplying hydrogen gas, ammonia gas, and Cp2Mg (which isa source gas for Mg) for 5-30 seconds into a crystal growth chamber. Thedelta-doped layer 155 is formed by delta-doping the P-type dopant at agrowth temperature of 700˜1000° C.

The undoped semiconductor layer 150 formed under the delta-doped layer155 can prevent the delta-doped second conductive type dopant from beingout-diffused, thereby preventing the surface characteristics of theactive layer 140 from being lowered.

The second conductive type semiconductor layer 160 is doped with asecond conductive type dopant, and functions as a second electrodecontact layer. The second conductive type semiconductor layer 160 may beformed of a P-type semiconductor layer, which is a III-V compoundsemiconductor having a composition formula of In_(x)Al_(y)Ga_(1-x-y)N(0≦x≦1, 0 y≦1, 0≦x+y≦1). For example, the P-type semiconductor layer maybe formed of at least one selected from the group consisting of GaN,InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. The second conductive typedopant is a P-type dopant, which comprises Mg, Zn, Ca, Sr, and Ba.

A hole concentration of the second conductive type semiconductor layer160 may be increased by the delta-doped layer 155 to improve theconductivity of the second conductive type semiconductor layer 160.Accordingly, the operating voltage of the light emitting device can bedecreased and the optical characteristic can be improved. The secondconductive type semiconductor layer 160 may be formed at a carrierconcentration of more than 1˜9×10¹⁸/cm³. Also, the delta-doped layer 155can suppress a dislocation defect to improve the crystallinity of thesemiconductor layer.

The second conductive type semiconductor layer 160 region may comprisethe delta-doped layer, or may comprise the undoped semiconductor layer150 and the delta-doped layer 155. That is, if the second conductivetype semiconductor layer 160 is not limited to the function as theelectrode contact layer, the second conductive type semiconductor layer160 may selectively comprise the layers on the active layer 140.However, the present invention is not limited thereto.

A transparent electrode layer (not shown) or/and a third conductive typesemiconductor layer (not shown) may be formed on the second conductivetype semiconductor layer 160. The third conductive type semiconductorlayer may be, for example, an N-type semiconductor layer. While theembodiment exemplarily describes that the first semiconductor layer 130is the N-type semiconductor layer and the second conductive typesemiconductor layer 160 is the P-type semiconductor layer, the reverseis also possible. The embodiment may comprise any one of a P-N junctionstructure, an N-P junction structure, an N-P-N junction structure, and aP-N-P junction structure.

FIG. 2 is a side sectional view of a lateral type semiconductor lightemitting device using FIG. 1. In the description of FIG. 2, therepetitive description for the same elements as those of FIG. 1 will beomitted.

Referring to FIG. 2, the lateral type semiconductor light emittingdevice 100A comprises a first electrode layer 181 formed on the firstconductive semiconductor layer 130. A second electrode layer 183 isformed on the second conductive type semiconductor layer 160. Herein, atransparent electrode layer (not shown) and a second electrode layer 183may be formed on the second conductive type semiconductor layer 160.

The first conductive type semiconductor layer 130 is exposed by a mesaetching process, and the first electrode layer 181 may be formed on theexposed first conductive type semiconductor layer 130.

When a forward bias is applied to the first electrode layer 181 and thesecond electrode layer 183, the number of holes injected into the activelayer 140 from the second conductive type semiconductor layer 160 andthe delta-doped layer 155 increases, so that the inner quantumefficiency of the active layer 140 can be improved.

FIG. 3 is a side sectional view of a vertical type semiconductor lightemitting device using FIG. 1. In the description of FIG. 3, therepetitive description for the same elements as those of FIG. 1 will beomitted.

Referring to FIG. 3, the vertical type semiconductor light emittingdevice 100B comprises a reflective electrode layer 170 on the secondconductive type semiconductor layer 160, and a conductive supportingsubstrate 175 on the reflective electrode layer 170. The reflectiveelectrode layer 170 may be selectively formed of Al, Ag, Pd, Rh or Pt,and the conductive supporting substrate 175 may be formed of Cu or Au.However, the present invention is not limited thereto.

The substrate 110 and the buffer layer 120 shown in FIG. 1 are removedby a physical or/and chemical method. In the physical method, a laserbeam having a predetermined wavelength is irradiated onto the substrate110 to separate the substrate 110, and the buffer layer 120 may beremoved by a wet or dry etching. In the chemical method, an etchant maybe injected into the buffer layer 120 to separate the substrate 110. Thebuffer layer 120 may be removed by a chemical etching. A first electrodelayer 181 may be formed under the first conductive type semiconductorlayer 130.

FIG. 4 is a side sectional view of a semiconductor light emitting deviceaccording to a second embodiment. In the first and second embodiments,like reference numbers will be used to refer to like parts. The sameparts as those of the first embodiment will not be described in thisembodiment.

Referring to FIG. 4, the semiconductor light emitting device 102comprises a substrate 110, a buffer layer 120, a first conductive typesemiconductor layer 130, an active layer 140, an undoped semiconductorlayer 150, a first delta-doped layer 155, and a second conductive typesemiconductor layer 160A.

The undoped semiconductor layer 150 may be, for example, an undoped GaNlayer. The undoped semiconductor layer 150 protects the active layer 140from a delta-doped second conductive type dopant.

A method for growing the undoped GaN layer exemplified as the undopedsemiconductor layer 150 is the same as that of the first embodiment, andtheir repetitive description will be omitted. The undoped semiconductorlayer 150 may be formed in a thickness of 5˜200 {hacek over (A)}. Anundoped Al_(y)GaN layer (0<y<0.5) may be grown on the undopedsemiconductor layer 150, and can prevent the operating voltage frombeing elevated.

The first delta-doped layer 155 is similar to the delta-doped layer ofthe first embodiment, and accordingly its concrete description will beomitted. The first delta-doped layer 155 may be formed at a thickness of1˜2 atomic layers (ex: 0.2˜0.5 nm) by delta-doping a second conductivetype dopant. The second conductive type dopant may comprise a P-typedopant, and the P-type dopant may comprise at least one selected fromthe group consisting of Mg, Zn, Ca, Sr and Ba.

The undoped semiconductor layer 150 formed under the first delta-dopedlayer 155 can prevent the delta-doped second conductive type dopant frombeing out-diffused, thereby preventing the surface characteristics ofthe active layer 140 from being lowered.

The second conductive type semiconductor layer 160A comprises a firstnitride semiconductor layer 161, a second delta-doped layer 163, and asecond nitride semiconductor layer 165. Herein, the second conductivesemiconductor layer 160A may be defined as comprising the undopedsemiconductor layer 150 to the second nitride semiconductor layer 165.However, the present invention is not limited thereto.

The first nitride semiconductor layer 161 may be realized by a secondconductive type formed on the first delta-doped layer 155. The firstnitride semiconductor layer 161 may be formed in a superlatticestructure of a second conductive type AlGaN layer or a second conductivetype AlGaN/GaN layer, and the second conductive type AlGaN/GaN layer maybe formed in 1 to 10 periods.

The first nitride semiconductor layer 161 comprises a second conductivetype dopant. The second conductive type dopant is a P-type dopant, whichcomprises Mg, Zn, Ca, Sr, or Ba. The first nitride semiconductor layer161 may be formed at a thickness of 5˜200 {hacek over (A)}.

The second delta-doped layer 163 is formed on the first nitridesemiconductor layer 161. The second delta-doped layer 163 may be formedat a thickness of 1˜2 atomic layers (ex: 0.2˜0.5 nm) by delta-doping asecond conductive type dopant. The second conductive type dopant maycomprise a P-type dopant, and the P-type dopant may comprise at leastone selected from the group consisting of Mg, Zn, Ca, Sr and Ba.

The second delta-doped layer 163 may be grown using Mg dopant. Forexample, an Mg delta-doped layer is grown by stopping the supply of agas source of trimethylgalium (TMGa) (or TEGa), exhausting the TMGa (orTEGa) gas to an outside, and supplying hydrogen gas, ammonia gas, andCp2Mg (which is a source gas for Mg) for 5˜30 seconds into a crystalgrowth chamber. The second delta-doped layer 163 is formed bydelta-doping the P-type dopant at a growth temperature of 700˜1000° C.

The second nitride semiconductor layer 165 is formed on the seconddelta-doped layer 163. The second nitride semiconductor layer 165 may beformed of a P-type semiconductor layer, which is a III-V compoundsemiconductor having a composition formula of In_(x)Al_(y)Ga_(1-x-y)N(0≦x≦1, 0≦y≦1, 0≦x+y≦1). The second conductive type dopant is a P-typedopant, and the P-type dopant may comprise Mg, Zn, Ca, Sr, or Ba.

A hole concentration of the second conductive type semiconductor layer160A may be increased by the first and second delta-doped layers 155 and163 to improve the conductivity of the second conductive typesemiconductor layer 160A. Accordingly, the operating voltage of thelight emitting device can be decreased and the optical characteristiccan be improved. The second conductive type semiconductor layer 160A maybe formed at a carrier concentration of more than 1˜9×10¹⁸/cm³.

Also, a third delta-doped layer (not shown) may be formed in the secondconductive type semiconductor layer 160A. The third delta-doped layermay be formed under a second electrode contact layer, and a concretedescription on the third delta-doped layer will be omitted.

By arranging the first and second delta-doped layers 155 and 163 betweenthe second nitride semiconductor layer 165 and the undoped semiconductorlayer 150, the conductivity of the second conductive type semiconductorlayer 160A can be improved, and a dislocation defect can be suppressedto improve the crystallinity. Also, the frequency of the delta doping isproportional to the hole concentration. Accordingly, an increase in thefrequency of the delta doping can decrease the operating voltage andimprove the optical characteristic. Moreover, the frequency of the deltadoping may be limited to a degree that does not deteriorate the qualityof the P-type semiconductor layer.

A transparent electrode layer (not shown) or/and a third conductive typesemiconductor layer (not shown) may be formed on the second conductivetype semiconductor layer 160A. The third conductive type semiconductorlayer may be, for example, an N-type semiconductor layer. While theembodiment exemplarily describes that the first semiconductor layer 130is the N-type semiconductor layer and the second conductive typesemiconductor layer 160 is the P-type semiconductor layer, the reverseis also possible. The embodiment may comprise any one of a P-N junctionstructure, an N-P junction structure, an N-P-N junction structure, and aP-N-P junction structure.

FIG. 5 is a side sectional view of a lateral type semiconductor lightemitting device using FIG. 4. In the description of FIG. 5, therepetitive description for the same elements as those of FIG. 4 will beomitted.

Referring to FIG. 5, the lateral type semiconductor light emittingdevice 102A comprises a first electrode layer 181 formed on the firstconductive semiconductor layer 130. A second electrode layer 183 isformed on a second nitride semiconductor layer 165 of the secondconductive type semiconductor layer 160A. Herein, a transparentelectrode layer (not shown) and a second electrode layer 183 may beformed on the second nitride semiconductor layer 165.

The first conductive type semiconductor layer 130 is exposed by a mesaetching process, and the first electrode layer 181 may be formed on theexposed first conductive type semiconductor layer 130.

When a forward bias is applied to the first electrode layer 181 and thesecond electrode layer 183, the number of holes injected into the activelayer 140 from the second conductive type semiconductor layer 160A andthe first and second delta-doped layers 155 and 163 increases, so thatthe inner quantum efficiency of the active layer 140 can be improved.

FIG. 6 is a side sectional view of a vertical type semiconductor lightemitting device using FIG. 4. In the description of FIG. 6, therepetitive description for the same elements as those of FIG. 4 will beomitted.

Referring to FIG. 6, the vertical type semiconductor light emittingdevice 102B comprises a reflective electrode layer 170 on the secondnitride semiconductor layer 165 of the second conductive typesemiconductor layer 160A, and a conductive supporting substrate 175 onthe reflective electrode layer 170. The reflective electrode layer 170may be selectively formed of Al, Ag, Pd, Rh or Pt, and the conductivesupporting substrate 175 may be formed of Cu or Au. However, the presentinvention is not limited thereto.

The substrate 110 and the buffer layer 120 shown in FIG. 4 are removedby a physical or/and chemical method. In the physical method, a laserbeam having a predetermined wavelength is irradiated onto the substrate110 to separate the substrate 110, and the buffer layer 120 may beremoved by a wet or dry etching. In the chemical method, an etchant maybe injected into the buffer layer 120 to separate the substrate 110. Thebuffer layer 120 may be removed by a chemical etching. A first electrodelayer 181 may be formed under the first conductive type semiconductorlayer 130.

In the embodiments, the active layer 140 is protected by the undopedsemiconductor layer 150, and at least one delta-doped layers 155, 163using a P-type dopant may be formed on the undoped semiconductor layer150. Accordingly, the hole concentration of the P-type semiconductorlayer can be improved and the dislocation defect can be suppressed toimprove the conductivity. Also, the electrical and optical efficienciesof the semiconductor light emitting device can be improved.

In the description of embodiments, it will be understood that when alayer (or film), region, pattern or structure is referred to as being‘on’ another layer (or film), region, pad or pattern, the terminology of‘on’ and ‘under’ comprises both the meanings of ‘directly on and under’and ‘indirectly on and under’. Further, the reference about ‘on’ and‘under’ each layer will be made on the basis of drawings. Also, thethickness of each layer in the drawings is an example, and is notlimited thereto.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is comprised in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A semiconductor light emitting device, comprising: a n-typesemiconductor layer including a semiconductor material having acomposition formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1);a delta-doped layer on the n-type semiconductor layer; an undopedsemiconductor layer on the delta-doped layer; an active layer on theundoped semiconductor layer; and a p-type semiconductor layer on theactive layer and including a semiconductor material having a compositionformula of In_(x)Al_(y)Ga_(1-x-y)N (0≦X≦1, 0≦y≦1, 0≦x+y≦1).
 2. Thesemiconductor light emitting device of claim 1, wherein the undopedsemiconductor layer comprises at least one of an undoped GaN layerand/or an undoped AlGaN layer.
 3. The semiconductor light emittingdevice of claim 1, wherein the undoped semiconductor layer has athickness of 5˜200 {hacek over (A)}.
 4. The semiconductor light emittingdevice of claim 1, wherein the a p-type semiconductor layer is on abuffer layer, and the buffer layer is on a substrate.
 5. Thesemiconductor light emitting device of claim 1, wherein the delta-dopedlayer comprises a first delta-doped layer and a second delta-dopedlayer.
 6. A semiconductor light emitting device, comprising a n-typesemiconductor layer including a semiconductor material having acomposition formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1);a delta-doped layer on the n-type semiconductor layer; a super latticelayer on the delta-doped layer; an undoped semiconductor layer on thesuper lattice layer; an active layer on the undoped semiconductor layer;and a p-type semiconductor layer on the active layer and including asemiconductor material having a composition formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦X≦1, 0≦y≦1, 0≦x+y≦1).
 7. The semiconductorlight emitting device of claim 6, wherein the undoped semiconductorlayer comprises at least one of an undoped GaN layer and/or an undopedAlGaN layer.
 8. The semiconductor light emitting device of claim 6,wherein the undoped semiconductor layer has a thickness of 5˜200 {hacekover (A)}.
 9. The semiconductor light emitting device of claim 6,wherein the a p-type semiconductor layer is on a buffer layer, and thebuffer layer is on a substrate.
 10. A semiconductor light emittingdevice, comprising: a n-type semiconductor layer including asemiconductor material having a composition formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1); a delta-doped layer onthe n-type semiconductor layer; an undoped semiconductor layer on thedelta-doped layer; an active layer on the undoped semiconductor layer;and a p-type AlGaN semiconductor layer on the active layer; a p-typesemiconductor layer on the p-type AlGaN semiconductor layer andincluding a semiconductor material having a composition formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦X≦1, 0≦y≦1, 0≦x+y≦1).
 11. The semiconductorlight emitting device of claim 10, wherein the undoped semiconductorlayer comprises at least one of an undoped GaN layer and/or an undopedAlGaN layer.
 12. The semiconductor light emitting device of claim 10,wherein the undoped semiconductor layer has a thickness of 5˜200 {hacekover (A)}.
 13. The semiconductor light emitting device of claim 10,wherein the a p-type semiconductor layer is on a buffer layer, and thebuffer layer is on a substrate.
 14. The semiconductor light emittingdevice of claim 10, wherein the delta-doped layer comprises a firstdelta-doped layer and a second delta-doped layer.